Methods: We used a state transition Markov model. Two strategies were compared: routine SBBs during esophagogastroduodenoscopy (EGD) in all patients with IDA regardless their celiac serology status (strategy A) vs SBBs only in IDA patients with positive serology (strategy B). The main outcomes were quality adjusted life years (QALY), average cost and the incremental cost effectiveness ratio (ICER). One way sensitivity analysis was performed on all variables and two way sensitivity analysis on selected variables were done. In order to validate the results, a Monte Carlo simulation of 100 sample trials with 10, and an acceptability curve were performed.

Results: Strategy A of routine SBBs yielded 19.888 QALYs with a cost of $218.10 compared to 19.887 QALYs and $234.17 in strategy B. In terms of cost-effectiveness, strategy A was the dominant strategy, as long as the cost of SBBs stayed less than $67. In addition, the ICER of strategy A was preferable, providing the cost of biopsy stays under $77. Monte Carlo simulation demonstrated that strategy A yielded the same QALY but with lower costs than strategy B.

Conclusion: Our model suggests that EGD with routine SBBs is a cost-effective approach with improved QALYs in patients with IDA when the prevalence of CD is 5% or greater. SBBs should be a routine screening tool for CD among patients with IDA, regardless of their celiac antibody status.

Mentions:
Our study has several limitations: we compared conducting SBBs unrelated to serological results assuming that the patients did not have a serological test, which reduced the total cost. However, in real practice, most patients would have had a serologic test done before facing the question whether or not to conduct an EGD with SBBs. Consequently testing the same outcomes, we applied our model, to a strategy of conducting SBBs in patients with IDA and negative serology. As Goddard et al[10] estimated, if the pretest probability of CD in patients presenting only with IDA is 5%, the post-test probability of CD is 0.3%. This means there is a need of duodenal biopsies from about 330 tTG antibody-negative patients to detect one extra patient with CD at an estimated additional cost of £35000 (about $50000). If the cost of SBBs is $60, the additional cost would be $19800. Under the assumptions of our model, the average cost of "No SBBs" strategy was $83.1 compared to $141.1 in the "SBBs" strategy (additional of $57.98). The average QALY in the "No SBBs" strategy was 19.4399 vs 19.4412 QALY in the "SBBs" strategy. The ICER was $45393 per QALY, which is still considered cost-effective (< $50000)[38]. However, when the cost of SBBs is higher than $60 the ICER increases and yield a non-cost-effective ICER. Since the cost of SBBs in our model was lower compared to the analysis performed by Goddard et al[10] we challenged our model by calculating SBBs with a higher cost, ranging between $50 to $120 (Figure 5A). Under these costs the ICER ranges between $37000 to $95000 per QALY. Our results revealed that as long as the utility of CD is less than 0.92, the ICER would still be under $50000 for 1 QALY (Figure 5B).

Mentions:
Our study has several limitations: we compared conducting SBBs unrelated to serological results assuming that the patients did not have a serological test, which reduced the total cost. However, in real practice, most patients would have had a serologic test done before facing the question whether or not to conduct an EGD with SBBs. Consequently testing the same outcomes, we applied our model, to a strategy of conducting SBBs in patients with IDA and negative serology. As Goddard et al[10] estimated, if the pretest probability of CD in patients presenting only with IDA is 5%, the post-test probability of CD is 0.3%. This means there is a need of duodenal biopsies from about 330 tTG antibody-negative patients to detect one extra patient with CD at an estimated additional cost of £35000 (about $50000). If the cost of SBBs is $60, the additional cost would be $19800. Under the assumptions of our model, the average cost of "No SBBs" strategy was $83.1 compared to $141.1 in the "SBBs" strategy (additional of $57.98). The average QALY in the "No SBBs" strategy was 19.4399 vs 19.4412 QALY in the "SBBs" strategy. The ICER was $45393 per QALY, which is still considered cost-effective (< $50000)[38]. However, when the cost of SBBs is higher than $60 the ICER increases and yield a non-cost-effective ICER. Since the cost of SBBs in our model was lower compared to the analysis performed by Goddard et al[10] we challenged our model by calculating SBBs with a higher cost, ranging between $50 to $120 (Figure 5A). Under these costs the ICER ranges between $37000 to $95000 per QALY. Our results revealed that as long as the utility of CD is less than 0.92, the ICER would still be under $50000 for 1 QALY (Figure 5B).

Methods: We used a state transition Markov model. Two strategies were compared: routine SBBs during esophagogastroduodenoscopy (EGD) in all patients with IDA regardless their celiac serology status (strategy A) vs SBBs only in IDA patients with positive serology (strategy B). The main outcomes were quality adjusted life years (QALY), average cost and the incremental cost effectiveness ratio (ICER). One way sensitivity analysis was performed on all variables and two way sensitivity analysis on selected variables were done. In order to validate the results, a Monte Carlo simulation of 100 sample trials with 10, and an acceptability curve were performed.

Results: Strategy A of routine SBBs yielded 19.888 QALYs with a cost of $218.10 compared to 19.887 QALYs and $234.17 in strategy B. In terms of cost-effectiveness, strategy A was the dominant strategy, as long as the cost of SBBs stayed less than $67. In addition, the ICER of strategy A was preferable, providing the cost of biopsy stays under $77. Monte Carlo simulation demonstrated that strategy A yielded the same QALY but with lower costs than strategy B.

Conclusion: Our model suggests that EGD with routine SBBs is a cost-effective approach with improved QALYs in patients with IDA when the prevalence of CD is 5% or greater. SBBs should be a routine screening tool for CD among patients with IDA, regardless of their celiac antibody status.